Phosphorus
Phosphorus is a key element in all known forms of life. Inorganic phosphorus in
the form of the phosphate plays a major role in biological molecules such as DNA
and RNA where it forms part of the structural backbone of these molecules.
Living cells also utilize phosphate to transport cellular energy via
adenosine triphosphate (ATP).
Nearly every cellular process that uses energy gets it in the form of ATP.
ATP is also important for phosphorylation, a key regulatory event in cells.
Phospholipids are the main structural components of all cellular membranes.
Calcium phosphate (Phosphorus) salts are used by animals to stiffen their
bones. An average person contains a little less than 1 kg of phosphorus, about
three quarters of which is present in bones and teeth in the form of apatite. A
well-fed adult in the industrialized world consumes and excretes about 1-3 g of
phosphorus per day in the form of phosphate.
In ecological terms, phosphorus is often a limiting nutrient in many
environments, i.e. the availability of phosphorus governs the rate of growth of
many organisms.
This is a particularly poisonous element with 50 mg being the average fatal
dose (white phosphorus is generally considered to be the lethal form of phosphorus
while phosphate and orthophosphate are essential nutrients). The allotrope white
phosphorus should be kept under water at all times as it presents a significant
fire hazard due to its extreme reactivity to atmospheric oxygen, and it should
only be manipulated with forceps since contact with skin may cause severe burns.
Chronic white phosphorus poisoning of unprotected workers leads to necrosis
of the jaw called "phossy-jaw" - poor wound healing in the mouth and
a breakdown of the jaw bone. The most common symptom of exposure to white phosphorus
is necrosis of the jaw.
Ingestion of white phosphorus may cause a medical condition known as "Smoking
Stool Syndrome". Organic compounds of phosphorus form a wide class of materials,
some of which are extremely toxic. Long-term absorption, particularly through
the lungs and the gastrointestinal tract, can cause chronic poisoning, which
leads to weakness, anemia, loss of appetite, gastrointestinal weakness, and
pallor.
Fluorophosphate esters are among the most potent neurotoxins known. A wide
range of organophosphorus compounds is used for their toxicity to certain
organisms as pesticides (herbicides, insecticides, fungicides etc). Most
inorganic phosphates are relatively nontoxic and essential nutrients. For
environmentally adverse effects of phosphates see eutrophication and algal
blooms.
Further Reading: National
Safety Council, Wiki
